=head1 Tasks that only need Perl knowledge
+=head2 Classify bug tickets by type
+
+Known bugs in Perl are tracked by L<https://rt.perl.org/> (which also
+includes Perl 6). A summary can be found at
+L<https://rt.perl.org/NoAuth/perl5/Overview.html>.
+It shows bugs classified by "type". However, the type of many of the
+bugs is "unknown". This greatly lowers the chances of them getting
+fixed, as the number of open bugs is overwhelming -- too many to wade
+through for someone to try to find the bugs in the parts of
+Perl that s/he knows well enough to try to fix. This task involves
+going through these bugs and classifying them into one or more types.
+
+=head2 Ongoing: investigate new bug reports
+
+When a bug report is filed, it would be very helpful to have someone do
+a quick investigation to see if it is a real problem, and to reply to
+the poster about it, asking for example code that reproduces the
+problem. Such code should be added to the test suite as TODO tests, and
+the ticket should be classified by type. To get started on this task,
+look at the tickets that are marked as "New Issues" in
+L<https://rt.perl.org/NoAuth/perl5/Overview.html>.
+
=head2 Migrate t/ from custom TAP generation
Many tests below F<t/> still generate TAP by "hand", rather than using library
quite a few tests in F<t/> have not been refactored to use it. Refactoring
any of these tests, one at a time, is a useful thing TODO.
-The subdirectories F<base>, F<cmd> and F<comp>, that contain the most
-basic tests, should be excluded from this task.
+The subdirectories F<base>, F<cmd>, F<comp> and F<opbasic>, that contain the
+most basic tests, should be excluded from this task.
=head2 Automate perldelta generation
hold him upside down and shake vigorously in order to actually extract the
cash.
+=head2 Write descriptions for all tests
+
+Many individual tests in the test suite lack descriptions (or names, or labels
+-- call them what you will). Many files completely lack descriptions, meaning
+that the only output you get is the test numbers. If all tests had
+descriptions, understanding what the tests are testing and why they sometimes
+fail would both get a whole lot easier.
+
=head2 Improve the coverage of the core tests
Use Devel::Cover to ascertain the core modules' test coverage, then add
=head2 fix tainting bugs
-Fix the bugs revealed by running the test suite with the C<-t> switch (via
-C<make test.taintwarn>).
+Fix the bugs revealed by running the test suite with the C<-t> switch.
+Setting the TEST_ARGS environment variable to C<-taintwarn> will accomplish
+this.
=head2 Dual life everything
Many diagnostic messages are not currently documented. The list is at the end
of t/porting/diag.t.
+=head2 Write TODO tests for open bugs
+
+Sometimes bugs get fixed as a side effect of something else, and
+the bug remains open because no one realizes that it has been fixed.
+Ideally, every open bug should have a TODO test in the core test suite.
+
+=head2 deparse warnings nicely
+
+Currently Deparse punts on deparsing the bitmask for warnings, which it
+dumps uglily as-is. Try running this:
+
+ $ ./perl -Ilib -MO=Deparse -e 'use warnings "pipe"; die'
+
+Deparse.pm could use the package variables in warnings.pm that warnings.pm
+itself uses to convert the list passed to it into a bitfield. Deparse just
+needs to reverse that.
+
+=head2 test and fix Deparse with perl's test suite
+
+If you run perl's tests with the TEST_ARGS environment variable set to
+C<-deparse> (e.g., run C<TEST=-deparse make test>), each test file will be
+deparsed and the deparsed output will be run. Currently there are many
+failures, which ought to be fixed. There is in F<Porting/deparse-skips.txt>
+a list of tests known to fail, but it is out of date. Updating it would
+also help.
+
+This is an incremental task. Every small bit helps. It is also a task that
+may never end. As new tests are added, they tickle corner cases that
+B::Deparse cannot yet handle correctly.
+
+This task I<may> need a bit of perl guts knowledge. But what changes need
+to be made is usually easy to see by dumping op trees with B::Concise:
+
+ $ ./perl -Ilib -MO=Concise -e 'foo(); print @_; die $$_'
+
+and adjusting B::Deparse to handle whatever you see B::Concise produce.
+This is also a good way to I<learn> how perl's op trees work.
+
=head1 Tasks that need a little sysadmin-type knowledge
Or if you prefer, tasks that you would learn from, and broaden your skills
=item *
- cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness
+ cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness
=item *
There are several scripts and tools for cross-compiling perl for other
platforms. However, these are somewhat inconsistent and scattered across the
codebase, none are documented well, none are clearly flexible enough to
-be confident that they can support any TARGET/HOST plaform pair other than
+be confident that they can support any TARGET/HOST platform pair other than
that which they were developed on, and it's not clear how bitrotted they are.
For example, C<Configure> understands C<-Dusecrosscompile> option. This option
is getting on for 5 years old, and requires insider knowledge of perl's
build system to draft a F<config.sh> for a new platform.
-Jess Robinson has sumbitted a grant to TPF to work on cleaning this up.
+Jess Robinson has submitted a grant to TPF to work on cleaning this up.
=head2 Split "linker" from "compiler"
On these systems, it might be the default compilation mode, and there
is currently no guarantee that passing no use64bitall option to the
Configure process will build a 32bit perl. Implementing -Duse32bit*
-options would be nice for perl 5.18.0.
+options would be nice for perl 5.26.0.
=head2 Profile Perl - am I hot or not?
One piece of Perl code that might make a good testbed is F<installman>.
-=head2 Allocate OPs from arenas
-
-Currently all new OP structures are individually malloc()ed and free()d.
-All C<malloc> implementations have space overheads, and are now as fast as
-custom allocates so it would both use less memory and less CPU to allocate
-the various OP structures from arenas. The SV arena code can probably be
-re-used for this.
-
-Note that Configuring perl with C<-Accflags=-DPL_OP_SLAB_ALLOC> will use
-Perl_Slab_alloc() to pack optrees into a contiguous block, which is
-probably superior to the use of OP arenas, esp. from a cache locality
-standpoint. See L<Profile Perl - am I hot or not?>.
-
=head2 Improve win32/wince.c
Currently, numerous functions look virtually, if not completely,
been written so that it reflects the state of the read-only attribute, even
for directories (whatever CRT is being used), for symmetry with chmod().)
-=head2 strcat(), strcpy(), strncat(), strncpy(), sprintf(), vsprintf()
-
-Maybe create a utility that checks after each libperl.a creation that
-none of the above (nor sprintf(), vsprintf(), or *SHUDDER* gets())
-ever creep back to libperl.a.
-
- nm libperl.a | ./miniperl -alne '$o = $F[0] if /:$/; print "$o $F[1]" if $F[0] eq "U" && $F[1] =~ /^(?:strn?c(?:at|py)|v?sprintf|gets)$/'
-
-Note, of course, that this will only tell whether B<your> platform
-is using those naughty interfaces.
-
-=head2 -D_FORTIFY_SOURCE=2
-
-Recent glibcs support C<-D_FORTIFY_SOURCE=2> which gives
-protection against various kinds of buffer overflow problems.
-It should probably be used for compiling Perl whenever available,
-Configure and/or hints files should be adjusted to probe for the
-availability of these feature and enable it as appropriate.
-
=head2 Arenas for GPs? For MAGIC?
C<struct gp> and C<struct magic> are both currently allocated by C<malloc>.
progressively update ExtUtils::ParseXS to generate OP implementations for
some XSUBs.
+=head2 Document how XS modules can install lexical subs
+
+There is an example in XS::APItest (look for C<lexical_import> in
+F<ext/XS-APItest/APItest.xs>). The documentation could be based on it.
+
=head2 Remove the use of SVs as temporaries in dump.c
F<dump.c> contains debugging routines to dump out the contains of perl data
Currently the %ENV entries are always byte strings.
See L</"Virtualize operating system access">.
+(See RT ticket #113536 for information on Win32's handling of %ENV,
+which was fixed to work with native ANSI codepage characters in the
+environment, but still doesn't work with other characters outside of
+that codepage present in the environment.)
+
=head2 Unicode and glob()
Currently glob patterns and filenames returned from File::Glob::glob()
system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid
running a shell. readpipe() (the function behind qx//) could be similarly
-extended.
+extended. Note that changing readpipe() itself may not be the solution, as
+it currently has unary precedence, and allowing a list would change the
+precedence.
=head2 Audit the code for destruction ordering assumptions
Change 25773 notes
- /* Need to check SvMAGICAL, as during global destruction it may be that
- AvARYLEN(av) has been freed before av, and hence the SvANY() pointer
- is now part of the linked list of SV heads, rather than pointing to
- the original body. */
- /* FIXME - audit the code for other bugs like this one. */
+ /* Need to check SvMAGICAL, as during global destruction it may be that
+ AvARYLEN(av) has been freed before av, and hence the SvANY() pointer
+ is now part of the linked list of SV heads, rather than pointing to
+ the original body. */
+ /* FIXME - audit the code for other bugs like this one. */
adding the C<SvMAGICAL> check to
have catgets().
For the really pure at heart, consider extending this item to cover
-also the warning messages (see L<perllexwarn>, C<warnings.pl>).
+also the warning messages (see L<warnings>, F<regen/warnings.pl>).
=head1 Tasks that need a knowledge of the interpreter
These tasks would need C knowledge, and knowledge of how the interpreter works,
or a willingness to learn.
+=head2 fix refaliasing with nested and recursive subroutines
+
+Currently aliasing lexical variables via reference only applies to the
+current subroutine, and does not propagate to inner closures, nor does
+aliasing of outer variables within closures propagate to the outer
+subroutine. This is because each subroutine has its own lexical pad and the
+aliasing works by changing which SV the pad points to.
+
+One possible way to fix this would be to create new ops for accessing
+variables that are closed over. So C<my $x; sub {$x}> would use a new op
+type, say C<padoutsv>, instead of the C<padsv> currently used in the
+sub. That new op would possibly check a flag or some such and see if it
+needs to fetch the variable from an outer pad. If we follow this approach,
+it should be possible at compile time to detect cases where the more
+complex C<padoutsv> op is unnecessary and revert back to the simpler,
+faster C<padsv>. There would need to be corresponding ops for arrays,
+hashes, and subs, too.
+
+There is also a related issue with recursion and C<state> variables. A
+subroutine actually has a list of lexical pads, each one used at a
+different recursion level. If a C<state> variable is aliased to another
+variable after a recursive call to the same subroutine, that higher call
+depth will not see the effect of aliasing, because the second pad will have
+been created already. Similarly, aliasing a state variable within a
+recursive call will not affect outer calls, even though all call depths are
+supposed to share the same C<state> variables.
+
+Both of these bugs affect C<foreach> aliasing, too.
+
=head2 forbid labels with keyword names
Currently C<goto keyword> "computes" the label value:
=head2 truncate() prototype
The prototype of truncate() is currently C<$$>. It should probably
-be C<*$> instead. (This is changed in F<opcode.pl>)
+be C<*$> instead. (This is changed in F<regen/opcodes>.)
=head2 error reporting of [$a ; $b]
do {...} block>. See the thread starting at
L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-09/msg00573.html>
+=head2 strict as warnings
+
+See L<http://markmail.org/message/vbrupaslr3bybmvk>, where Joshua ben Jore
+writes: I've been of the opinion that everything strict.pm does ought to be
+able to considered just warnings that have been promoted to 'FATAL'.
+
=head2 lexicals used only once
This warns:
debugger on a running Perl program, although I'm not sure how it would be
done." ssh and screen do this with named pipes in /tmp. Maybe we can too.
-=head2 LVALUE functions for lists
+=head2 regexp optimizer optional
-The old perltodo notes that lvalue functions don't work for list or hash
-slices. This would be good to fix.
-
-=head2 regexp optimiser optional
-
-The regexp optimiser is not optional. It should configurable to be, to allow
-its performance to be measured, and its bugs to be easily demonstrated.
+The regexp optimizer is not optional. It should be configurable to be optional
+and to allow its performance to be measured and its bugs to be easily
+demonstrated.
=head2 C</w> regex modifier
This would allow proposals such as short circuiting sort to be implemented
as a module on CPAN.
-=head2 lexical aliases
-
-Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>).
-
=head2 Self-ties
Self-ties are currently illegal because they caused too many segfaults. Maybe
=head2 Virtualize operating system access
Implement a set of "vtables" that virtualizes operating system access
-(open(), mkdir(), unlink(), readdir(), getenv(), etc.) At the very
-least these interfaces should take SVs as "name" arguments instead of
-bare char pointers; probably the most flexible and extensible way
-would be for the Perl-facing interfaces to accept HVs. The system
-needs to be per-operating-system and per-file-system
-hookable/filterable, preferably both from XS and Perl level
-(L<perlport/"Files and Filesystems"> is good reading at this point,
-in fact, all of L<perlport> is.)
+(chdir(), chmod(), dbmopen(), getenv(), glob(), link(), mkdir(), open(),
+opendir(), readdir(), rename(), rmdir(), stat(), sysopen(), uname(),
+unlink(), etc.) At the very least these interfaces should take SVs as
+"name" arguments instead of bare char pointers; probably the most
+flexible and extensible way would be for the Perl-facing interfaces to
+accept HVs. The system needs to be per-operating-system and
+per-file-system hookable/filterable, preferably both from XS and Perl
+level (L<perlport/"Files and Filesystems"> is good reading at this
+point, in fact, all of L<perlport> is.)
This has actually already been implemented (but only for Win32),
take a look at F<iperlsys.h> and F<win32/perlhost.h>. While all Win32
See also L</"Extend PerlIO and PerlIO::Scalar">.
-=head2 Store the current pad in the OP slab allocator
-
-=for clarification
-I hope that I got that "current pad" part correct
-
-Currently we leak ops in various cases of parse failure. I suggested that we
-could solve this by always using the op slab allocator, and walking it to
-free ops. Dave comments that as some ops are already freed during optree
-creation one would have to mark which ops are freed, and not double free them
-when walking the slab. He notes that one problem with this is that for some ops
-you have to know which pad was current at the time of allocation, which does
-change. I suggested storing a pointer to the current pad in the memory allocated
-for the slab, and swapping to a new slab each time the pad changes. Dave thinks
-that this would work.
-
=head2 repack the optree
+B<Note:> This entry was written in reference to the I<old> slab allocator,
+removed in commit 7aef8e5bd14.
+
Repacking the optree after execution order is determined could allow
removal of NULL ops, and optimal ordering of OPs with respect to cache-line
-filling. The slab allocator could be reused for this purpose. I think that
+filling. I think that
the best way to do this is to make it an optional step just before the
completed optree is attached to anything else, and to use the slab allocator
-unchanged, so that freeing ops is identical whether or not this step runs.
+unchanged--but allocate a single slab the right size, avoiding partial
+slabs--, so that freeing ops is identical whether or not this step runs.
Note that the slab allocator allocates ops downwards in memory, so one would
have to actually "allocate" the ops in reverse-execution order to get them
contiguous in memory in execution order.
use warnings;
my $undef;
-
+
if ($undef == 3) {
} elsif ($undef == 0) {
}
use warnings;
my $undef;
-
+
my $a = $undef + 1;
my $b
= $undef
would produce this output
- Use of uninitialized value $undef in addition (+) at wrong.pl line 4.
- Use of uninitialized value $undef in addition (+) at wrong.pl line 7.
+ Use of uninitialized value $undef in addition (+) at wrong.pl line 4.
+ Use of uninitialized value $undef in addition (+) at wrong.pl line 7.
(rather than lines 4 and 5), but this would seem to require every OP to carry
(at least) line number information.
What might work is to have an optional line number in memory just before the
BASEOP structure, with a flag bit in the op to say whether it's present.
Initially during compile every OP would carry its line number. Then add a late
-pass to the optimiser (potentially combined with L</repack the optree>) which
+pass to the optimizer (potentially combined with L</repack the optree>) which
looks at the two ops on every edge of the graph of the execution path. If
the line number changes, flags the destination OP with this information.
Once all paths are traced, replace every op with the flag with a
C<0oddddd>, parallel to the existing construct to specify hex constants
C<0xddddd>
+=head2 Revisit the regex super-linear cache code
+
+Perl executes regexes using the traditional backtracking algorithm, which
+makes it possible to implement a variety of powerful pattern-matching
+features (like embedded code blocks), at the cost of taking exponential time
+to run on some pathological patterns. The exponential-time problem is
+mitigated by the I<super-linear cache>, which detects when we're processing
+such a pathological pattern, and does some additional bookkeeping to avoid
+much of the work. However, that code has bit-rotted a little; some patterns
+don't make as much use of it as they should. The proposal is to analyse
+where the current cache code has problems, and extend it to cover those cases.
+
+See also
+L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2013-01/msg00339.html>
+
=head1 Big projects
Tasks that will get your name mentioned in the description of the "Highlights
-of 5.18.0"
+of 5.26.0"
=head2 make ithreads more robust
Fix Perl_sv_dup, et al so that threads can return objects.
-=head2 Add class set operations to regexp engine
-
-Apparently these are quite useful. Anyway, Jeffery Friedl wants them.
-
-demerphq has this on his todo list, but right at the bottom.
-
-
=head1 Tasks for microperl
https://perl5.git.perl.org / perl5.git / blobdiff